1. Field of the Invention
The present invention relates to a horizontally-opposed type engine for a motorcycle, in which a pair of left and right cylinder heads are connected to a pair of left and right cylinder blocks in such a manner that combustion chambers are formed between each of the cylinder blocks containing a plurality of cylinder bores disposed in parallel with the axial lines thereof extending substantially in the horizontal direction and pistons slidably fitted in the cylinder bores; a crank shaft is disposed in such a manner as to be perpendicular to the axial lines of the cylinder bores; and the engine is mounted on the motorcycle with the axial line of the crank shaft extending in the longitudinal direction.
2. Description of Background Prior Art
The horizontally-opposed type engine of this type has been generally configured such that exhaust passages are provided in cylinder heads protruded on the left and right sides of a motorcycle in such a manner as to be simply opened downwardly.
It may be desirable to make a bank angle of a motorcycle at a relatively large value; however, in the horizontally-opposed type engine, since exhaust pipes are connected to the bottom surfaces of cylinder heads protruded on both sides of the motorcycle, the bank angle of the motorcycle is restricted by the presence of the exhaust pipes.